Coronary artery embryogenesis in cardiac defects induced by retinoic acid in mice.

BACKGROUND: Although normal coronary artery embryogenesis is well described in the literature, little is known about the development of coronary vessels in abnormal hearts. METHODS: We used an animal model of retinoic acid (RA)-evoked outflow tract malformations (e.g., double outlet right ventricle [DORV], transposition of the great arteries [TGA], and common truncus arteriosus [CTA]) to study the embryogenesis of coronary arteries using endothelial cell markers (anti-PECAM-1 antibodies and Griffonia simplicifolia I (GSI) lectin). These markers were applied to serial sections of staged mouse hearts to demonstrate the location of coronary artery primordia. RESULTS: In malformations with a dextropositioned aorta, the shape of the peritruncal plexus, from which the coronary arteries develop, differed from that of control hearts. This difference in the shape of the early capillary plexus in the control and RA-treated hearts depends on the position of the aorta relative to the pulmonary trunk. In both normal and RA-treated hearts, there are several capillary penetrations to each aortic sinus facing the pulmonary trunk, but eventually only 1 coronary artery establishes patency with 1 aortic sinus. CONCLUSIONS: The abnormal location of the vessel primordia induces defective courses of coronary arteries; creates fistulas, a single coronary artery, and dilated vessel lumens; and leaves certain areas of the heart devoid of coronary artery branches. RA-evoked heart malformations may be a useful model for elucidating abnormal patterns of coronary artery development and may shed some light on the angiogenesis of coronary artery formation.

Tetralogy of Fallot, truncus arteriosus, abnormal myocardial architecture and anomalies of the aortic arch system induced by bis-diamine in rat fetuses.

OBJECTIVES: The aim of this study was to analyze the relation between anomalies of the heart and aortic arch arteries in near-term rat fetuses exposed to the chemical bis-diamine. BACKGROUND: Bis-diamine is known to induce cardiovascular anomalies. METHODS: Bis-diamine was given orally to normal pregnant rats, and the 65 fetuses were examined under a dissecting microscope after formalin fixation. RESULTS: There were 26 rat fetuses (40%) with a ventricular septal defect in the perimembranous portion, of which 14 (22%) had tetralogy of Fallot, 4 (6%) had truncus arteriosus and 8 (12%) had a relatively small defect with no other major anomalies. In 44 fetuses (68%) the middle latitudinal muscle bundle of the ventricular septum was continuous with the right ventricular free wall. There were, isolated or in association, a double- or right aortic arch in 6 fetuses (9%), aberrant subclavian arteries in 9 (14%), right ductus arteriosus in 12 (18%) and agenetic ductus in 4 (6%). The cross-sectional area of the ductus, as corrected by that of the aortic isthmus, was abnormally small in 47 rats (72%). The rat fetuses with a septal defect or abnormal myocardial architecture, or both, usually had a small ductus; it was very small or absent in those fetuses with tetralogy of Fallot. Of the four fetuses with truncus arteriosus, two had a vestigial vasculature on the truncus root and three had a rudimentary infundibulum. CONCLUSIONS: The cardinal defect may be the anomalous and reduced development of the sixth arch arteries, which by imposing pressure overload on the fetal right ventricle, may have led to either or both the persistence of ventricular septal defect as a vent or the formation of myocardial architecture favorable for the generation of pressure in the right ventricle.

Cardiovascular anomalies in chick embryos produced by bis-diamine in dimethylsulfoxide.

N,N'-bis(dichloroacetyl)-1,8-octamethylenediamine(bis-diamin e) (100 micrograms) dissolved in dimethylsulfoxide (DMSO) was administered to early developing chick embryos (Hamburger-Hamilton stage 9-21) in order to clarify the teratogenic effects on the cardiovascular system and to determine whether bis-diamine interferes with the migration of neural crest cells. Of 346 cases, 154 (44.5%) survived. The incidence of cardiovascular anomalies was 149 out of 154 cases (96.8%). Infundibular ventricular septal defect, double outlet right ventricle, and persistent truncus arteriosus were the primary cardiac anomalies observed in this study. A high percentage of these anomalies were accompanied by hypoplasia of the right 6th aortic arch artery and persistent left 4th aortic arch artery. Particularly, administration of bis-diamine to chick embryos at stage 13 resulted in a high incidence of persistent truncus arteriosus (64.3%). Bis-diamine has been suspected to inhibiting the migration of neural crest cells. However, neural crest cells were observed in the tunica media of the great arteries and the truncal valves of persistent truncus arteriosus produced by bis-diamine in chimeric embryos at stage 13. Morphological changes such as cell death were not observed.

Pathogenesis of persistent truncus arteriosus induced by nimustine hydrochloride in chick embryos.

Nimustine hydrochloride (ACNU) is a nitrosourea derivative anticancer agent which has been shown to cause persistent truncus arteriosus in chick embryos. The objective of this study was to confirm the teratogenic effects of ACNU on the cardiovascular system of chick embryos and to determine whether ACNU induces persistent truncus arteriosus by interfering with neural crest cells. Various doses of ACNU ranging from 10 to 200 micrograms were injected under the chorioallantoic membrane of chick embryos on the third day of incubation. Saline solution was used as the control. After 10 to 11 days of incubation, 242 (46%) survivors of the 524 treated eggs were obtained. The survival rates of the embryos and the frequencies of cardiovascular anomalies were dose dependent. Of 146 embryos with cardiovascular anomalies, 104 (71%) had persistent truncus arteriosus. Ventricular septal defect and double-outlet right ventricle were seen in 37 (25%) and one (1%), respectively. Aortic arch anomalies were seen in 116 embryos (79%). Quail-chick chimeras (chick embryos with quail cardiac neural crest) were treated with 50 micrograms of ACNU and examined histologically 24 hours later. These chimeras showed dying neural crest cells in the pharyngeal arches. Dying cells were also noted in the neural tube, cranial ganglia, retina, and otocyst. These results suggest that persistent truncus arteriosus in chick embryos treated with ACNU is induced by neural crest cell death.

Cardiovascular anomalies produced by nimustine hydrochloride in the rat fetus.

The cardiovascular teratogenicity of nimustine hydrochloride (ACNU) was studied in rat fetuses. This drug is a nitrosourea derivative anticancer agent and produces alkylation of DNA. Pregnant Donryu rats were treated with single doses of 10, 11 or 13 mg/kg of the teratogen at various stages during gestation. Examination of the hearts was performed by microdissection after sacrificing the animals on the 20th day of gestation. The highest frequency of cardiovascular anomalies was found in the groups treated on the 8th day of gestation, but there was no difference in the rates induced by the three dosages of ACNU administered. The most common cardiovascular anomalies observed were ventricular septal defect (76.8%) and double outlet right ventricle (10.3%). A considerable number of affected fetuses (37/263) showed complex cardiac anomalies with atrioventricular (AV) malalignment and other AV valve anomalies. These anomalies include: double inlet left ventricle, straddling AV valve, atresia or stenosis of the AV valve, and dysplastic AV valve. ACNU appears to be a useful teratogenic agent for inducing complexes of cardiac anomalies which include AV malalignment.

An aborted human fetus with truncus arteriosus communis--possible teratogenic effect of Tedral.

We recently performed a detailed anatomicopathologic examination on an aborted human embryo whose mother had taken four tablets of Tedral (one tablet of Tedral contains 130 mg theophylline, 25 mg ephedrine, 8 mg phenobarbital) for an upper respiratory tract infection when the embryo was at approximately 30 days of development. On the same day, the mother developed acute chest pain and a fast, irregular heart beat. The abortion occurred at approximately 80 days of gestation. The heart of the fetus showed truncus arteriosus (Van Praagh type A1). Although no direct cause and effect relationship was proven in this case, the possibility of a teratogenic effect of Tedral during early pregnancy is considered.

Syndromes of cardiovascular malformations induced by copper citrate in hamsters.

Pregnant golden hamsters were injected intraperitoneally on the morning of the eighth day of gestation with a solution of copper citrate (2.7 mg/kg) or deionized water. Embryos were removed from the mothers by laparotomy on the 12th and 13th days of gestation, serially sectioned through the thorax, and examined for cardiac malformations. Twenty-one of the 37 edematous embryos from copper-treated mothers were affected with a total of 58 major cardiac anomalies. Sixteen of these embryos were affected with double outlet right ventricle in association with a membranous ventricular septal defect, two embryos contained hearts with overriding aortas, and three embryos were affected with isolated ventricular septal defects. Eleven of the 16 embryos with double outlet right ventricle were also affected with pulmonary trunk hypoplasia. The concept that these cardiac anomalies arise from a common pathogenetic basis is supported by the present model.